For \(T_{b3}\rightarrow T_8\ell ^+\ell ^-\)  decays, the single-quark transition contributions are strongly dominant so
that other contributions like the \(W\) -exchange contributions are usually omitted.
The SU(3) flavor structure Hamiltonian with \(b\rightarrow s,d\)  transitions can been found, for instance, in Refs. [1]}, [2]}, [3]}, and the SU(3) IRA hadronic helicity amplitudes for \(T_{b3}\rightarrow T_{8}\ell ^+\ell ^-\)  via \(b\rightarrow s/d \ell ^+\ell ^-\)  can be parametrized as
\(H(T_{b3} \rightarrow T_8\ell ^+\ell ^-)^{L(R),s_p,s_k}_{VA,\lambda }&=&e_1(T_{b3})^{[ij]}T(\bar{3})^k(T_8)_{[ij]k}+e_2(T_{b3})^{[ij]}T(3)^k(T_8)_{[ik]j},\) 
